In an interventional treatment (intravascular treatment), which is one kind of treatment for aneurysms, or in an angiographic examination, a catheter is inserted into a blood vessel for example from the groin until the catheter goes through the blood vessel to reach a target part. For a process of sending the catheter (or a guide wire for guiding the catheter) to a target location, there has been a roadmap function that superimposes an X-ray fluoroscopic image on a 3D (three-dimensional) vascular image displaying the image. A practitioner can lead the catheter or guide wire to an affected part while viewing a displayed roadmap. The roadmap function is expected to be effective in reducing the examination time and the amount of a contrast agent.
As one kind of treatment for cerebral aneurysms, there is a method of putting a coil-like obstructive material into an aneurysm from the tip of a catheter and keeping the obstructive material therein to cause blood to clot in the aneurysm and block the flow of blood, thereby preventing the rupture of the aneurysm. The treatment method is typically referred to as coiling. In a coiling operation, the displaying of a 3D roadmap, for which a previously reconstructed 3D vascular image is used as a map, is effective. By the way, in the coiling, first a coil of a large size is placed and kept. Then, a coil of a small size is placed and kept in order to gradually close a gap.
However, in the conventional way of displaying a 3D roadmap, it is difficult to distinguish between an already separated coil and a new coil that will be placed and kept. Therefore, the disadvantage is that it is difficult to figure out the state of a coil that is already placed and kept.